| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem related to an optical element.SOLUTION: An optical element includes a light-emitting curved surface and a bottom surface situated at an opposite side of the light-emitting curved surface. Combination of the light-emitting curved surface and the bottom surface defines a negative lens part, two first positive lens parts, and two second positive lens parts. The first positive lens parts and the second positive lens parts are arranged one after the other and surround the negative lens part. The first positive lens parts have a first curvature, the second positive lens parts have a second curvature, and the second curvature is smaller than the first curvature. |
